Extension rail systems have been used to enable a drawer, and therefore its receptacle, to be fully extended out of a housing, such as a medication cart. Most extension rail systems are like those found in filing cabinets. These systems usually employ two extension rail assemblies, one assembly mounted on either side of the drawer receptacle. Each assembly usually comprises three interacting rails, with one of the rails being fixed to the receptacle, one of the rails being fixed to a vertical wall in the housing and a third or intermediate rail being located between the other two rails in each assembly. Typically, these rails are made of thin gage steel or other similar metal and many employ roller or ball bearing type assemblies which enable the three rails of each assembly to slidably interact along their length.
While this type of extension rail system is often associated with filing cabinets, they have also been employed for the drawers used in carts for storing and dispensing medication. Such medication carts often employ locking mechanisms for preventing the drawers from inadvertently extending open. In addition, security systems are often used with these locking mechanisms to limit access to authorized personnel. Such extension rail systems often suffer from a number of drawbacks. For example, the rails are susceptible to being permanently bent when the drawer is fully extended, and the roller or bearing assemblies are susceptible to being damaged. Once the rails are bent or the roller or bearing assemblies damaged, the rails are likely to bind or jam, making it difficult or even impossible to fully open or close the drawer (i.e. fully extend or retract the rails). If the rails become bent and jam to the point of preventing the drawer from being fully opened, access to medication located in the drawer may be blocked. If the drawer is prevented from being fully closed, then the locking mechanism and the security system may be inoperative. PG,4 Such damage to the rail system would necessitate repairs which typically requires a maintenance mechanic and prevents at least the subject drawer from being used while repairs are conducted. Putting the entire cart or even just one drawer out of commission while repairs are conducted often wrecks routines and disrupts the dispensing of patient medication.
To perform properly, these metal extension rail systems require lubrication. When the drawers are fully extended, portions of the metal rails are exposed. Thus, medication dispensing personnel are susceptible to having their clothing or their person soiled by the lubrication. While most of the personnel who dispense medication from such carts are not required to be sterile, they are typically required to maintain a degree of cleanliness, such as clean hands and clean clothing. Therefore, an extension rail system which did not need lubrication would be desirable for use in such medication carts.
In the medication dispensing industry there is a need for various styles of medication storage and dispensing carts. These carts are used in a number of facilities such as hospitals, nursing homes and the like. Each such facility often has medication dispensing carts specially tailored to their individual requirements. For example, for a given cart design, one facility may require one combination of drawer sizes and another facility may require a different combination of drawer sizes. However, with existing extension rail systems, where the rails are fixed to the cart, adapting each cart to the needs of any given customer is typically labor intensive and expensive. Essentially, each cart has to be custom built. Manufacturing custom carts tailored to the needs of each facility could be economical if most of the components used to build the carts were standardized and easily interchangeable to adapt to each facilities requirements.
In some applications, the drawer receptacles are made removable. For example, sometimes the medication is held in re-usable containers which are stored in the drawer receptacle and the containers are cycle filled. In cycle filling, when the medication is consumed, the drawer receptacle with all its empty containers is removed and taken to a pharmacy or other prescription filling facility where the containers are refilled with the appropriate medication. The drawer receptacle and the now filled containers are then returned to the medication dispensing facility. These removable drawer receptacles have typically been made of metal and shaped like a box. To accommodate the different size medication containers used by its customers, manufacturers of these medication carts have had to produce and inventory different size receptacles. One type drawer designed to accommodate such receptacles has a tray with an extension rail assembly fixed to each side and the removable receptacle sitting on the tray.